ArbitraryInterface

Rasuvaeff\PropertyTesting\ArbitraryInterface

Interface — Source

Describes a space of random values with integrated shrinking.

An arbitrary produces a Shrinkable via generate(): the generated value together with a lazy tree of smaller candidates, each carrying its own subtree. The property runner reads the value, and on a failure descends through the tree, accepting the first candidate that still fails, until no smaller value fails — yielding a minimal counterexample.

Because shrink candidates are attached at generation time, combinators such as Gen::map() and Gen::flatMap() shrink in the source domain and re-apply their transformation; implementations never need to invert a transformed value.

Methods

generate()

generate(Random $random): Shrinkable

Produce one random value from this arbitrary's space, together with its shrink tree. Candidates must be ordered most aggressive first (typically toward a zero/empty/identity element) and every branch of the tree must be finite, so shrinking terminates.